RL02K Pack Reliability/Characteristics

[Pete Turnbull]

On 30/03/2015 10:28, Johnny Billquist wrote:
> On 2015-03-30 07:47, Christopher Parish wrote:
>> I've gotten my RL-02 -> USB Mass Storage controller mostly working
>> with a few residual gremlins.  Specifically, I've noticed from my
>> testing that I have good packs, ones that read out almost the same
>> every time, and bad packs, ones where half the bits seem to be in
>> different states every time I read them.

> I have not had any problems with long term reliability. I have packs
> that are 20 years old that read just fine.

I've got some with 35-year old data, written around 1980, that are fine.

> I suspect you have some issues with your controller, and I wouldn't
> think it was timing, but I really don't know enough at this point to
> make any smart comments.

Christopher, have you tried more than one drive?  I have a problem with 
one particular pack I was trying to make bootable.  It shows no bad 
blocks but after successfully SYSGENning a new RT-11 system, any attempt 
to make it bootable on Unit 1 failed; it was fine on Unit 0, and still 
fine on that unit (what was Unit 0) if the unit select plugs were 
swapped to operate it as Unit 1.  The drive passes all the diagnostics 
except seek timing using the Oscillating Seek test.  It looks like a DC 
servo problem in the drive, but I'll know for sure later today or 
tomorrow when I've done some more work on it.

You could also have damaged packs.  I have one that is OK on the low 
numbered tracks yet unreliable on the later ones, and I wasn't surprised 
to find it has visible damage near the centre.

-- 
Pete

Pete Turnbull